Blockages in the ureter which are generally caused by constriction thereof, such as a stenosis and/or the presence of kidney stones, can lead to serious medical problems such as pain, inflammation of the ureter wall and prevention of urine drainage from the kidney.
A ureteral catheter, sometimes also called ureteral or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney and/or to ensure the patency of a ureter. The provision of a ureteral catheter may be a temporary provision, but a ureteral catheter may also placed in the ureter for longer periods. The length of the ureteral catheter used in adult patients may for example vary between 24 to 30 cm.
One or both ends of the ureteral catheter may be coiled to prevent it, after placement, from moving out of place. Such ureteral catheter is often referred to as a double J catheter or also JJ catheter or pig-tail catheter.
A ureteral catheter can be placed in the ureter cystoscopically or percutaneously. In the first method, the ureteral catheter is introduced into the ureter from the bladder towards the kidney of the patient. In a percutaneous placement method of the ureteral catheter, the ureteral catheter is inserted through an incision into the patient's body and brought into the kidney and subsequently through the ureter until a distal end of the catheter reaches a desired location in the bladder.
In both methods, accurate placement of the ureter catheter is important. In particular, the catheter ends in both the pyelum and bladder should be correctly placed to avoid tissue damage and/or discomfort to the patient.
The ureteral catheter may be connected with a proximal end to a distal end of a so-called pusher catheter with which the ureteral catheter can be moved towards and into the desired implantation position. When the ureteral catheter is correctly positioned, the ureteral catheter may be released from the pusher catheter, and the pusher catheter can be pulled back out of the body of the patient being treated.
For proper placement of the ureteral catheter an easy release of the ureteral catheter from the pusher catheter is desirable. At the same an unintentional and/or premature release of the ureteral catheter is undesirable, in particular when the ureteral catheter has not yet been positioned at the desired location in the ureter. Unintentional and/or premature release may for instance occur when the combination of pusher catheter and ureteral catheter is pulled back, i.e. in proximal direction. Generally, unintentional and/or premature release of the ureteral catheter should be prevented.
To avoid such premature release of the ureteral catheter from the pusher catheter, it is known to provide a tether, which is connected to the ureteral catheter. When the combination of pusher catheter and ureteral catheter is pulled back, i.e. in proximal direction, the tether may be pulled to reduce the risk of unintentional and/or premature release of the ureteral catheter.